A fuel reformer is operated to reform a hydrocarbon fuel into a reformate gas. In the case of an onboard fuel reformer such as a fuel reformer associated with a vehicle or a stationary power generator, the reformate gas produced by the fuel reformer may be utilized as fuel or fuel additive in the operation of an internal combustion engine. The reformate gas may also be utilized to regenerate or otherwise condition an emission abatement device associated with an internal combustion engine or as a fuel for a fuel cell.